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Emergency crews are on the scene of a hazardous materials incident in the East Bay City of Vallejo after between 80 and 100 workers reported being overcome by some kind of fumes, according to the Solano County office of emergency services. (Published Friday, Mar 30, 2012)

Updated at 2:34 PM PST on Saturday, Mar 31, 2012

Nearly 100 people who suffered nausea, dizziness and breathing problems from a carbon dioxide leak at a Vallejo food processing plant Friday were treated at Solano and Napa County hospitals, a fire captain said.

The one person who was considered to be in serious condition has been released from the hospital.

A spokesman for Sutter Solano Medical Center says the patient was released around 10 p.m. Friday after his condition stabilized. The name, age or any other details about the patient have not been released.

The patient was one of the many workers at Ghiringhelli Specialty Foods in Vallejo who were exposed to the gas Friday that firefighters say was caused by a leak from an external carbon dioxide tank.

Vallejo Fire Capt. Marty Culverwell says nearly all workers at the plant suffered at least some effects from the gas.

The California Division of Occupational Safety and Health was investigating the incident.

A spokesperson with the Vallejo Fire Department tells us that the substance, possibly carbon dioxide, may have sickened the workers while they were preparing salads.

Co-owner Mike Ghiringhelli told NBC Bay Area that the air inside the plant has tested clean throughout the day. He said it would continue to be tested.

"The key indicator you look for is air quality and everything is good in that department." Ghiringhelli said.

Ghiringhelli hinted that the sickness might have been caused by anxiety and not CO2. He also made it clear he wanted all of his employees to be checked out, adding his top concern was for his staff.

First responders said they didn't expect workers to suffer long-term effects from the exposure.

Ghiringhelli is a food processing facility that make salads, pizzas and grilled meats.

Helicopter video over the scene showed several dozen people in a triage-type area on the grass and in the parking lot of the plant. They were sitting upright and did not appear to be in distress. One by one the workers were lead off to waiting ambulances. Many of them walked to the ambulance with the help of paramedics and did not need stretchers.

Ninety-five people were treated at Sutter Solano Medical Center, Kaiser Permanente Vallejo Medical Center, both in Vallejo, the NorthBay Medical Center in Fairfield and Queen of the Valley Medical Center in Napa, Culverwell said. Twenty ambulances and two buses transported the patients.

Sutter Solano Medical Center said one male patient was admitted and was in serious condition.

Triage tents were set up at the hospital parking lots. The injured were processed through one of two large pop-up type structures before they were allowed into the emergency room.

The tents are often used as a precaution in hazmat situations. Patients are screened there before going into a medical facility.

Dozens more workers gathered to get instructions outside the plant. It was not immediately clear if the plant would be closed for the entire day.